1. Technical Field
The present disclosure generally relates to hinge mechanisms, and more particularly to a hinge mechanism applied in an electronic device.
2. Description of Related Art
Many electronic devices include hinge mechanisms. A hinge mechanism generally includes a cam and a cam follower resisting the cam to ensure that one part is capable of rotating or being maintained at predetermined positions relative to the other. Thus, a changeable friction force is generated therebetween.
A commonly used hinge mechanism includes a pivot shaft, two frames, and two special purpose irregular washers resisting each other. One irregular washer forms two protrusions and the other irregular washer defines two cutouts engaging with the protrusions thereof. The frames and the irregular washers are sleeved on the pivot shaft. The main frame is connected to the display frame of the electronic device. The irregular washer with the protrusions defines a noncircular hole therein corresponding to the cross-section of the pivot shaft, and the irregular washer with the cutouts defines a substantially circular hole therein and forms a locking pole fixed to one of the frames. Therefore, the irregular washer with the protrusions rotates with the pivot shaft relative to the irregular washer with cutouts and the frame is fixed to the irregular washer with cutouts.
In use, the protrusion washer slides along the pivot shaft and resists different portions of the recess washer, and thereby, the resisting force along the axis direction of the pivot shaft is changed. However, since the shape and size of the noncircular hole in the irregular washer with protrusions is similar to that of the cross-section of the pivot shaft, the inner sidewalls of the noncircular hole have a relatively large contact surface with the pivot shaft, which prevents the irregular washer from sliding along the pivot shaft smoothly. Furthermore, the irregular washer and the pivot shaft are scraped severely.
Therefore, there is room for improvement within the art.